A single failure means you are no longer an independent diver and you are totally reliant on your buddy to ensure you don't drown or get bent. No where in technical diving is this appropriate. From day one dive planning is all about being able to independently survive at least one equipment failure without assistance. To me this is even more important in rebreather diving as the system is simply more complex. More seals, scrubber, one way valves, maybe electronics, and so forth.
The idea of "I can't carry enough gas to complete the dive" is just a symptom of a bigger problem: poor equipment configuration, lack of physical ability (either skills or fitness to do the dive), or lack of discipline (lazy, not managing bottom times, reluctance to buy the required gear, diving off a boat that's not equipped to accommodate the planes dive, etc).
Team bailout is bad practice.